The invention relates in general to electronic devices and more specifically to an apparatus, system, and method for electrostatic discharge (ESD) protection in an electronic device.
Electronic devices such as, for example, cellular telephones, personal digital assistants (PDA), portable media players, and portable computers are susceptible to damage by electrostatic discharge (ESD). ESD is the rapid and spontaneous transfer of electrical charge between two objects. One example of ESD that can be experienced particularly in dry climates includes the “shock” or spark resulting from the discharge of electrostatic charge when a hand or figure is placed near a doorknob after the electrostatic charge has formed due to shuffling across carpet. ESD occurs in a variety of situations, however, and does not need to be felt to cause extensive damage to sensitive components in electronic devices. Keypads, buttons, and other user interfaces on electronic devices provide an especially vulnerable entry point for electrostatic charges to reach electronic device components.
Some conventional designs reduce the susceptibility of electronic devices to ESD by increasing the thickness of insulating materials at the vulnerable areas. For example, the thickness of the shaped rubber layer forming the keypad of a device can be increased to insulate the sensitive components from ESD. This technique is limited in that, due to the increased thickness, the size of the overall size of the electronic device is increased. Further, the electronic device may be more difficult and costly to manufacture since the thicker keypad requires more material and is more difficult to manipulate. Also, the thicker material may result in a keypad that is bulkier, less sensitive, and more difficult to use.
Other conventional techniques for reducing susceptibility to ESD include the placement of circuit elements such as diodes to “short out” ESD and direct charges to ground. These methods, however, are limited in that the complexity and cost of the electronic device is increased.
Other conventional designs include a conductive escutcheon that surrounds at least some of the buttons of a keypad and is connected to the ground of the electronic device. This technique is limited in that the escutcheon is difficult and costly to manufacture. Further, the escutcheon often can not be shaped to adequately protect the areas that are vulnerable to ESD penetration. For example, as the sizes of the keys of keypads decrease, the available space for positioning the sections of the conductive escutcheon also decreases resulting in device areas that are not adequately protected against ESD.
Accordingly, there is a need for an apparatus, system, and method for electrostatic discharge (ESD) protection in an electronic device.